Magnetic amplifier



April 27, 1954 F. J. RAU 2,677,099

MAGNETIC AMPLIFIER Filed March 29,. 1952 3 Sheets-Sheet 1 1954 .F. J. RAu

MAGNETIC AMPLIFIER April 27 3 Sheets-Sheet 2 Filed March 29, 1952 Fi'g.3.

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April 27, 1954 Filed March 29, 1952 F. J. RAU

MAGNETIC AMPLIFIER 3 Sheets-Sheet I5 Patented Apr. 27, 1954 MAGNETIC AMPLIFIER Frank J. Rau, Pittsburgh, Pa., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 29, 1952, Serial N o. 279,327

Claims.

This invention relates to induction apparatus and in particular to magnetic ampliers of the push-pull type.

In the past, push-pull magnetic ampliners which receive their control signal from a phase sensitive demodulator or any other device having a similar voltage output utilize a separate biasing winding and bias voltage supply. Inasmuch as the winding operation on a magnetic amplier represents a large percentage of the works cost, the use of a separate biasing winding and a separate control winding greatly increases the cost of manufacture. Not only does the use of these two separate windings increase the cost of manufacture, but it also increases the size of the wound core members, thus increasing the overall size and weight of the magnetic amplifier. This is a disadvantage, particularly in such fields as aircraft in which the size of the apparatus incorporated into the ship is extremely important. In addition, the use of a separate bias voltage supply increases the cost of manufacture and the overall size of the apparatus.

An object of this invention is to provide for receiving voltages from a phase sensitive demodulator or any other device having a similar voltage output and so applying them to the control winding of a push-pull magnetic amplifier that each control winding functions as both a biasing winding and a control winding.

Another object of this invention is to provide for receiving variable control signals and sub stantially constant reference signals from a phase sensitive demodulator and so applying the resultants of these signals, as formed by a variable and a constant signal, to the control windings of a push-pull magnetic amplier that each control winding functions as both a biasing winding and a control winding.

A further object of this invention is to provide for receiving variable control signals and substantially constant reference signals from a phase sensitive demodulator and so applying the resultants of these signals, as formed by a variable and a constant signal to the control windings of a push-pull magnetic amplifier that the oonstant biasing portion of each resultant signal appearing across its associated control winding can be readily varied.

Other objects of this invention will become apparent when taken in conjunction with the accompanying drawings in which:

Figure l is a schematic diagram of one embodiment of the teachings of this invention;

Fig. 2 is a schematic diagram of another embodiment of the teachings of this invention in which a different type 0f phase sensitive demodulator is utilized;

Fig. 3 is a schematic diagram illustrating still another embodiment of the teachings of this in vention in which alternating current is applied to the reactor windings of the magnetic amplifier in a diiierent manner;

Fig. 4 is a schematic diagram illustrating still another embodiment of the teachings of this invention, and

Fig. 5 is a schematic diagram illustrating a still further embodiment of the teachings of this invention in which a different type of core member is used in the magnetic amplifier.

Referring to Fig. 1 of the drawings, a pushpull magnetic amplier is illustrated generally at I0 and it comprises four rectangular magnetic core members I2, I4, I6 and IB. ln order to magnetize the core members I2, Ill, I5 and I8, a predetermined amount, a plurality of reactor windings 20, 22, 24 and 2S, respectively, are disposed in inductive relationship therewith.

For the purpose of permitting the passage of current in only one direction through the reactor windings 20, 22, 24 and 26, self-saturating rectifiers 28, 30, 32 and 34, respectively, are provided. As illustrated, the rectifiers 28 and 3Q are connected in series circuit relationship, one terminal of the rectifier 28 being connected to one end of the reactor winding 26 and one terminal of the rectifier 30 being connected to one end of the reactor winding 22. In like manner, the rectifiers 32 and 34 are connected in series circuit relationship, one of the terminals of the rectier 32 being connected to one end of the reactor winding 24 and one terminal of the rectier 34 being connected to one end of the reactor winding 25.

In this instance, two load rectifiers 35 and 3S are connected in series circuit relationship, one terminal of the rectifier 36 being connected to the other end of the reactor winding 2i! and one terminal of the rectifier 38 being connected to the other end of the reactor winding 22. The rectiiiers 36 and 38 are disposed to so block the flow of current that the ow is in only one direction through a load 40, during each hah cycle of an alternating current supply voltage 4I. As

illustrated, the load 40 comprises an energizing winding of a solenoid 42 and it is electrically connected across the series connected rectiiiers 3@ and 38.

In like manner, in order to block the ow of amplifier I is in a balanced condition and a movable contact member HI of a relay H3 is in the position shown in the drawings. However, when a variable control voltage is applied to the primary winding 92 of the transformer 90, the magnetic amplifier I0 becomes unbalanced so that the movable contact member I I I engages either a stationary contact member I I4 or a stationary contact member Ii or the relay H3, to thus complete energizing circuits to apparatus not shown. The direction of this unbalance de pends upon the polarity of the voltage across the primary winding 92 of the transformer 90 with respect to the polarity of the voltage across the primary winding 82 of the transformer 80. Still referring to Fig. l, assuming the biasing voltage across the secondary winding 8d of the transformer Bil is of greater magnitude than the variable control voltage across the sections Sli and 96 of the transformer et, the current ow through the control windings 5E, l53, G and 62 will produce a nun that opposes the flux produced by the current flow through the reactor windings 2|), 22, 24 and 26, respectively.

Assume for purposes of illustration that the polarity of the voltages across the windings of the transformers 8S and Sii are as shown in the drawings and that ve volts appear across the sections 86 and 32 of the transformer 8o and that two volts appear across each of the sections t, |00, |02 and Ii of the transformer 90. When this condition exists three volts will appear across the resistor l@ and seven volts will appear across the resistor '52. The seven volts appearing across the resistor 'I2 will aiect a current ilow through the variable resistance element ld, and the control windings GB and S2, which in turn will decrease the magnetization 01"' the core members I6 and I 8, respectively. This action increases the impedance of the reactor windings 24 and 26, respectively, and thus decreases the current ow through the energizing winding d3 of solenoid 49. Under such a condition, the movable contact member III is rbrought into circuit closing position with the stationary contact member I Iii of the relay IIS to thus complete an energizing circuit to apparatus not shown. The three volts appearing across the resistor lo likewise effects an actuation of the movable contact member I I E into circuit closing position with the stationary contact member H, since it decreases the current ow through the control windings 55 and 58 to thus increase the magnetization of the core members I2 and Ell, respectively. Such action decreases the impedance of the reactor windings 2G and 22, respectively, and thus increases the current flow through the energizing winding d@ of the solenoid 32.

Assuming the polarities across the windings of the transformer Si) are opposite to that shown in the drawings and the polarities of the windings of the transformer 82 are as shown in the drawings,

a larger voltage will appear across the resistor 'IIJ than across the resistor i2. When this condition exists the larger voltage across the resistor 'It effects a decrease in the magnetization of the core members I2 and III to thus increase the impedance of the reactor windings 2|) and 22, respectively, decreasing the current flow through the energizing winding it of the solenoid i2 to thereby actuate the movable contact member I I i of the relay I I3 into circuit closing position with the stationary contact member I It. The smaller voltage appearing across the resistor 'I2 likewise effects an actuation of the movable contact mem- 6.. ber I into circuit closing position with the stationary contact member IIS since it effects an increase in the magnetization of the core members I6 and I 8 to thus decrease the impedance of the reactor windings 24 and 26, respectively, to

thereby increase the current ow through the' B0 and 62 can be varied to thus eiiect different biasing potentials across each of these control windings. However, if only one biasing voltage is desired the variable resistor 'ifi may be replaced by a fixed resistor (not shown).

Although Fig. 1 of the drawings has been described as comprising the energizing windings 40 and 43 which actuate a pivotal member |28 to thus complete an electrical circuit through either the stationary contact members ||4 or l Iii to apparatus not shown, it is to ybe understood thatr other types of loads (not shown) could be connected to be responsive to the voltage across the series connected rectiers 36 and 38 and the voltage across the series connected rectiers 46 and 48.

It is also to be understood that the biasing voltage applied to the resistors lil and 'i2 and thus to the control windings 5&2, 53, Si) and 62 could be reversed by changing the direction of the rectiers |66, |08, IIB, II2 in the demodulator 73 or by reversing the direction in which the control windings 55, 58, tII and 62 are wound on their respective core members. If such a change were made, the magnetic amplifier I0 would unbalance in an opposite direction to that above-described for the same given polarities across the windings of the transformers 39 and Si).

Referring to Fig. 2 of the drawings, there is illustrated another embodiment of the teachings of this invention, and like components of Figs. l and 2 have been given the same reference characters. The main distinction between the apparatus of Figures l and 2 is that in Fig. 2, a half-wave demodulator |2I is used instead of the full-wave demodulator 'I3 shown in Fig. l.

As illustrated, the demodulator |2I is electrie cally connected to the resistors 'I0 and 'I2 of Fig. 2. In this instance the demodulator |2i comprises a potential transformer |22 having a primary Vwinding |24 across which is applied a substantially constant biasing voltage and a secondary winding |26. The demodulator |2I likewise comprises a potential transformer i3d having a primary winding E32 across which is applied a variable control voltage and a secondary winding |34 comprising sections |36 and ISii.

The energizing circuit for applying the substantially constant biasing voltage appearing` across the secondary winding I2@ of the transformer |22 and the variable control voltage appearing across the section itt of the transformer |36 to the resistor 'I extends from one end of the resistor 'I' through a rectifier |139, the section |36 of the transformer E32, and the secondary winding |26 of the transformer |22, to the other end of the resistor iii. Gn the other hand, the circuit for applying the substantially constant biasing voltage appearing across the secondary winding |25 of the transformer |22 and the variable control Voltage appearing across the' section |32 of the transformer |32 to the resistor 12 extends from one end of the resistor 12 through a rectifier M2, the section |38 of the transformer |313, and the secondary winding |28 of the transformer |22, to the other end of the resistor 12.

Since the dernodulator |2| is only a half-wave demodulator, no voltages will appear across the resistors 18 and 12 during the half cycle when the polarities of the windings of the transformers |22 and |39 are opposite to those polarities shown in Fig. 2 of the drawing. Also, since the remainder of the apparatus shown in Fig. 2 of the drawing is identical to the corresponding apparatus of Fig. l, its description and operation is considered unnecessary.

Referring to Fig. 3 of the drawings, there is illustrated another embodiment of the teachings of this invention. Like components of Figs. 1 and 3 have been given the saine reference characters. The main distinction between the apparatus of Figs. 1 and 3 is in the manner of applying the alternating supply voltage to the reactor windings 2t, 22, 24 and 26. In addition, control windings 58' and 62 are used in place of the control windings 58 and 32, respectively, o Fig. 1 since the control windings 58 and 62' are wound oppositely from the control windings 53 and @2, respectively. This is necessary since the current flow through the reactor windings 22 and 26 of Fig. 1 is in a direction opposite to the current new 'through the reactor windings 22 and 26, respectively, of Fig. 3.

In order to permit the flow of current in only one direction through the reactor windings 2li, 22, 24 2t, self-saturating rectii-ers |52, E52, |54 and |55, respectively, are rovided. As illustrated, the rectiers and |552 are connected in series circuit relationship and are oppositely poled in the series circuit, one terminal of the rectier lili! being connected to on3 end of the reactor winding 2li, and one terminal of the rectifier |52 being connected to one end of the reactor winding 22. In like manner, the rectiiiers |54 and i555 are connected in series circuit relationship and are oppositely poled in the series circuit, one terminal of the rectier 54 being connected to one end of the reactor winding 24 and one terminal of the rectifier E56 being connected to one end of the reactor winding 2E.

In order to supply energy to the reactor' windings 2li, 22, 24 and 25 of 3, a transformer 69 having prin-lary winding lili! and a center* tapped secondary winding itil is rovided. As illustrated, an energizing circuit for the reactor winding 2t during one haii cycle of an alternating current supply i558 extends from one end of the secondary winding tijd of the transformer ll! through the reactor winding 2t, the rectiiier |52. and the energizing winding .13 of the solenoid is to the center-tap of the secondary winding EM. During the same half cycle of the alternating current supply E66, an energizing circuit for the reactor winding 22 extends from the same end of the secondary winding ld through the reactor winding 22, the rectifier |52 and the energizing winding fill of the solenoid 42 to the center-tap of the secondary winding |64. On the other hand, during the other half cycle of alternating current supply Hit, an energizing circuit for the reactor winding 22 extends from one end of the secondary winding |84 through the reactor winding 2li, the rectifier |54, and the energizing 'winding of the solenoid 49, to the center tap of the secondary winding |64.

' flux produced During the same half cycle of the alternating current supply IE6, an energizing circuit for the reactor winding 22 extends from one end of the secondary winding |64 through the reactor Winding 20, the rectifier |5, and the energizing winding 40 of the solenoid 42, to the center tap of the secondary winding |64.

Since the operation of the apparatus of Fig. 3 is substantially identical to the operation of the apparatus of Fig. l, a description of such operation is considered unnecessary.

Referring to Fig. 4 of the drawings, there is illustrated still another embodiment of the teachings of this invention, in which like components of Figs. 2, 3 and 4 have been given the same reference characters. The main distinction between the apparatus shown in Figs. 3 and 4 is that in the apparatus of Fig. 4, the halfwave deinodulator i2! of Fig. 2 is substituted for the fnll-wave dernodulator i3 of Fig. 3.

Since the operation of the apparatus of Fig. 4 is substantially identical to the operation of the apparatus of Fig. 2, a description of such opera tion is considered unnecessary.

Referring to 5 ci the drawings, there is illustrated a still further embodiment of the teachings of this invention, in which like components of Figs. l and 5 have been given the same reference characters. The main distinction between the apparatus shown in Figs. 1 and 5 is that in the apparatus of Fig. 5, two three-legged magnetic core members 225i and 222 are substr1 tilted for the four rectangular core members |2, |4, I6 and |l of Fig. 1. Such an interchangeability in push-pull magnetic amplifiers between rectangular and threedegged core members is well known in the art. In addition, the reactor windings 22 and 2S of l. are replaced in Fig. 5 by reactor windings 22 and 2li and they are wound oppositely from the windings 22 and 26 of Fig. 1.

When utilizing the threeelegged core members 2532 and 222 of 5, it is only necessary to provide two control windings 224 and 286, one disposed in inductive relationship with each of the core members 22s and 222, respectively. Such being the case, in order to apply the variable control voltage and the biasing voltage appearing across the resistor 'it to the control winding 204, the resistor in, the variable resistance element 14, and the control winding 2&4 are connected in series circuit relationship. rl'hus, the control winding 224 is responsive to both the variable control voltage and the biasing voltage. In order to apply the variable control voltage and the biasing voltage appearing across the resistor '|2 to the control winding 205, the resistor 12, the variable resistance element irl, and the control winding 2255 are connected in series circuit relationship.

As illustrated, the control winding 204 is disposed on the middle leg of the core member 200 and the current iiow therethrough produces a iiux in the core member 202 that opposes the in the core member 200 by the current iiow through the reactor windings 2D and 22', provided the polarity of the voltages across the resistors lil and 'i2 are as shown in the drawing. The control winding 206 is also so disposed on the middle leg of the core member 2M that the current flow therethrough produces a flux in the core member 222 that opposes the flux produced in the core member by the current new through the reactor windings 24 and 26. Of course, it is to be understood .that if the rectiers I|06, |08,

.and thus the Iiux produced by kthrough the control winding 20st would be additive to the iiux produced by the current flow Ht and H 2 of the demodulator 13 were reversed in direction, the current flow through the control windings 204 and 205 would be in an opposite direction the current ilow through the reactor windings 2B and 22', and the flux produced by the current flow through the control winding 205 would likewise be additive to the iiux produced by the current flow through the reactor windings 2li and 2t.

Since the operation of the apparatus of Fig. 5 is substantially identical to the operation of the apparatus of Fig. 1, a description of such operation is considered unnecessary.

It is to be understood that two threelegged core members, could also be substituted for the core members l2, I4, it and i8 of Figs. 2, 3 and 4.

Although the invention has been described with reference to certain specific embodiments thereof, numerous modicaticns falling within the spirit and scope of the invention are possible.

I claim as my invention:

1. In a push-pull magnetic amplifier, the combination comprising, a plurality of magnetic core members, a reactor winding disposed in inductive relationship with each of the magnetic core members, a rectifier in series circuit relationship with each of the reactor windings so as to permit passage of current in only one direction therethrough, means for applying an alternating current voltage to each of the series connected reactor windings and rectiners, a control winding disposed in inductive relationship with each of the magnetic core members, two resistors connected in series circuit relationship, electrical apparatus electrically connected to the resistors for producing both a substantially constant biasing voltage and a variable control voltage across each of the resistors, a resistance element, circuit means for connecting one of said two resistors, the resistance element, and one of the control windings in series circuit relationship, another circuit means for connecting the other oi said two resistors, the resistance element, and another of the control windings in series circuit relationship so that each control winding functions as both a biasing winding and a control winding, and means responsive to the current ilow through the reactor windings and actuated in response to the variable control voltage across each of said two resistors to perform a predetermined operation.

2. In a push-pull magnetic ampliiier, the combination comprising, a plurality of magnetic core members, a reactor winding disposed in inductive relationship with each of the magnetic core members, a rectifier in series circuit relationship with each of the reactor windings so as to permit passage of current in only one direction therethrough, means for applying an alternating current voltage to each of the series connected reactor windings and rectiiiers, a control winding disposed in inductive relationship with each of the magnetic core members, two resistors connected in series circuit relationship, a phase sensitive demodulator electrically connected to the two resistors so that both a substantially constant biasing voltage and a variable control voltage appear across each of the two resistors, a variable resistance element, circuit means for connecting one of the two resistors, the variable resistance element, and one of the control windings in series circuit relationship, another circuit means for bination comprising,

`connecting the other of said two resistors, the .variable resistance element, and another of the control windings in series circuit relationship so that each control winding functions as both a .windings and actuated in response to the variable Icontrol Voltage across each of the two resistors to permit a predetermined operation.

3. In a push-pull magnetic ampliler, the comfour magnetic core members, a reactor winding disposed in inductive relationship with each of the magnetic core members, a rectifier connected in series circuit relationship with each of the reactor windings for permitting current to flow in only one direction therethrough, means for applying an alternating current voltage to each of the series connected reactor windings and rectiers, a control winding disposed in inductive relationship with each of the core members, two resistors connected in series circuit relationship, a phase sensitive demodulator electrically connected to the two resistors so that both a substantially constant biasing voltage and a variable control voltage appear across each of the two resistors, a resistance element, circuit means for connecting one oi the two resistors, the resistance element, and two of the control windings in series circuit relationship, another circuit means for electrically connecting the other of said two resistors, the resistance element, and the other two control windings in series circuit relationship so that each control winding functions as both a biasing winding and a control winding, and means responsive to the current flow through the reactor windings and actuated in response to the variable control voltage across each of said two resistors to perform a predetermined operation.

4. In a push-pull magnetic amplier, the combination comprising, two three-legged magnetic core members, two reactor windings disposed in inductive relationship with each of the core members, a rectier connected in series circuit relationship with each of the reactor windings for permitting current to iiow in only one direction therethrough, means for applying an alternating current voltage to each of the series connected reactor windings and rectiers, a control winding disposed in inductive relationship with each of the core members, two resistors connected in series circuit relationship, a phase sensitive demodulator electrically connected to the two resisters so that both a substantially constant biasing voltage and a variable control voltage appear across each of the two resistors, a resistance element, circuit means for electrically connecting one of the two resistors, the resistance element, and one of the control windings in series circuit relationship, another circuit means for connecting the other of said two resistors, the resistance element, and the other control winding in series circuit relationship so that each control winding functions as both a control winding and a biasing winding, and means responsive to the current now through the reactor windings and actuated in response to the variable control voltage across each oi said two resistors to perform a predetermined operation.

5. In a push-pull magnetic amplifier, the combination comprising, four magnetic core members, a reactor winding disposed in inductive relationship with each of the magnetic core members, a rectifier connected in series circuit relationship with each of the reactor windings for permitting current to flow in only one direction therethrough, means for applying an alternating current voltage to each of the series connected reactor windings and rectifiers, a control winding disposed in inductive relationship with each of the core members, two resistors connected in series circuit relationship, electrical apparatus electrically connected to the two resistors for producing both a substantially constant biasing voltage and a variable control voltage across each of the two resistors, a variable resistance element, circuit means for electrically connecting one or the two resistors, the variable resistance element, and two of the control windings in series circuit relationship, another circuit means for electrically connecting the other of said two resistors, the Variable resistance element, and the other two control windings in series circuit relationship so that each control winding functions as both a biasing winding and a control winding, and so that the magnitude of the Voltage across each of the control windings can be varied by means of the Variable resistance element, and means responsive to the current flow through the reactor windings and actuated in response to the variable control Voltage across each of said two resistors to perform a predetermined operation.

No references cited. 

